A toner supply roll of an electrophotographic machine supplies toner to a developing roll and cleans the developing roll (scrapes to collect the remaining toner). In order to improve the toner carrying performance and the cleaning performance, the toner supply roll is made of a foam (sponge). The foam includes on its surface a plurality of recesses made by opened foam cells, and cell walls defining the surface recesses. Conventionally, the toner is carried by physically being stored in the surface recesses, and cleaning was performed by scraping the remaining toner by the cell walls. In recent years, in addition to physically carrying and cleaning the toner, it is considered to carry and clean the toner by using an electric attractive force by imparting conductivity to the foam to apply a voltage to the foam.
For example, Patent Document 1 is known as the conductive foam roll. Patent Document 1 describes adding an ionic conductive agent to a conductive foam layer.